Multiple gpu configuration

[evilmeister13]

On both AMD and Nvidia's websites they claim that if you were to get two or more gpus that it would double your performance. Is this true? For example, if i got two 290x, would it give me double perfomance compared to just one? Or is it just another one of those things that only gives you a small boost and isnt really worth it?

[Dmon]

It'd give 85-90% boost with the 2nd one.

[BrightCandle]

Depends on the game. The real answer is anywhere from nothing to 100% where most often its around 80-90%. Its actually reasonably good scaling in games that are very graphically intense.

[evilmeister13]

Typical with amd, they were advertising bf4 and thief. How would it affect them?

[zapsyou]

I found this video to be quite helpful covers several titles and show performance and temp difference (varies slightly from card to card but will yield similar results)

 

[acidydragon]

SLI/Crossfire scale AMAZINGLY with two GPU's now a days. 

Just about every game that is coming onto the market now supports both Crossfire, and SLI.

 

You'll get 80-90% of the performance on the second GPU, which isn't 100%, but it's pretty darn close.

[evilmeister13]

Thanks guys got a lot of insight. Hmm. Looking at 3 or maybe even 4 cards now.

[BrightCandle]

Thanks guys got a lot of insight. Hmm. Looking at 3 or maybe even 4 cards now.

 

The situation starts to change once you go above 2 cards however. 3 cards often doesn't scale to another 50% performance and 4th cards only rarely improve performance at all, its not uncommon infact for 4 cards to perform worse than 3. 

[evilmeister13]

Oh. Damn you computers. Why must you be so complicated?

[BrightCandle]

Oh. Damn you computers. Why must you be so complicated?

 

Well when you are talking about dropping $4k on graphics cards your putting yourself into a very small group of enthusiasts!

[Mao_Zedong]

You guys are wrong, in one game (i don't remember what) with dual 650 ti boosts it was around 105% increase. In general though, it is around 80-90%

[BrightCandle]

You guys are wrong, in one game (i don't remember what) with dual 650 ti boosts it was around 105% increase. In general though, it is around 80-90%

 

And I have had in F1 2012 the FPS scale -75%. Its definitely outside of those ranges occasionally, and it certainly doesn't always work when the game is released. But mostly its within a reasonable range.

 

Quite a lot of games are CPU limited once you start getting SLI levels of performance, a lot of the less graphically intense ones rarely get up to 120fps or so even if you want them too. Its much more complicated than just 80-90% but that doesn't mean its wrong, its mostly true just not universally so.

[-rascal-]

@digitalnav (member of Digital Storm) did some multi-GPU testing a while back.

 

http://linustechtips.com/main/topic/78152-amd-r9-290x-2x-3x-4x-crossfire-4k-resolution-overclocking-benchmarks/

In the above thread, he ran some gaming benchmarks with one, two, three, and four way CrossfireX with the R9-290X. The results are pretty interesting; you should have a quick look.

 

He did a similar test with the GTX 780 (or is it GTX 780Ti?) as well. I will try to dig that up for you as well.

 

EDIT: Oh here it is. one, two, three, and four way SLi with the GTX 780Ti.

http://linustechtips.com/main/topic/78480-nvidia-gtx-780ti-2x-3x-4x-sli-4k-overclocking-benchmarks/

[GamerDude]

You guys are wrong, in one game (i don't remember what) with dual 650 ti boosts it was around 105% increase. In general though, it is around 80-90%

Even if this is true, one or two games that scale exceptionally well are the exception rather than the norm. I've been running CF and SLi systems for a long time now, and dual card CF/SLi scaling is pretty good these days.....up to 90% in some game. When a game really doesn't like CF/SLi, you may even get negative scaling though, that is, two cards framerate is lower than with one card.

 

When you dabble with 2-3 card configs, you learn to deal with some issues that crop up with games, especially newer ones....but when CF/SLi scale as they should, the result can be breath-taking.